Night (Morning) Terror

One of the many blessings that make up Reagan, which include her burgening sense of humor and unstoppable cuteness, is her sleeping habits...
She sleeps. At night when it is time for bed she goes to be. No fight, no fuss. And she sleeps all night 98 percent of the time. Earlier this Fall she was released from the confinement of a crib, and now sleeps free-range. She is still her crib but one of the walls have been removed.
As I said she sleeps. Sometimes she sleeps in. When everbody else is up at 7:30 a.m. Reagan has been known to sleep until 8:30 a.m., giving dear old Dad a chance to drink some hot coffee for a change.
One morning about two weeks ago. Everbody is up and moving. I am getting Tiernan dressed and dealing with the minutia of why Tiernan needs to where a long sleeve sweater over his Cars themed short-sleeve shirt in December or calmly explaining, for the fourth time, why the shoe on his left foot should really be on his right foot. And I was able to focus on getting Tiernan dressed and take the time to get into a serious discussion about why it is necesary to comb ones hair. (Which by the way, brought some serious social and philosophical quesions, about free expression and society's need to put labels on people.)
I was able to question why humans need to cut, style, comb, dye, blow dry, streak, perm, braid, and generally manipulate their quaffs because Reagan was still asleep. I thought, "Boy she must be going through a growth spurt. It is best to let her sleep."
I finally got the boy dressed and combed and it was time to descend the stairs and begin breakfast ritual. Prior to going down stairs, I thought it'd be very fatherly if I just popped in to check on Reagan. Imagine my surprise when her bed is devoid of Reagan. There is no Reagan in the bed. I grab her blankets and shake them, check under her bed, check her closet. No Reagan in the room. It is Reaganless. "Reagan!" I yell. At this point, I am in a bit of panic. I bound down the strairs searching for my daughter. She's not in the kitchen, not in the basement playroom, not in the nook, not in the den. The front door is still locked. The back door is shut, but can be opened from the inside, even while locked. I run out to back yard, "Reagan!!!" The gate is closed. If she got out, she'd be trapped in the yard. She's not in the yard.
I stop in the living room, and listen. I hear the faint breathing of a child. I hone in on it and discover, my little girl sleeping peacefully on the chair-and-half in the living room. She is nestled comfily in to the pillows like a puppy. She is snoring ever so cutely.
But the quesiton, quickly becomes, how long has she been down here? She could have come down here ten minutes ago, she could have come down at 3 a.m. My wife walked right past her on her way to work. I walked passed her twice while I was looking for her. I think we're gonna have to make sure that gate at the top of the stair is closed every night.